The invention relates to the decoration of articles, and more particularly to decorations by labels transferred from a web.
In web transfer decorating, it is desired to coordinate movement of web bearing labels with the movement of the article to which the label is to be applied. Coordination poses significant problems, for the linear velocity of the web must match the linear velocity of the article surface, otherwise label distortion results. One approach, taken in U.S. Pat. No. 4,300,974 to Bauer, is to drive the web at a fixed velocity, while moving the article at a varied velocity, thus maintaining matched linear velocities at the contact area for complex article shapes. A cam having a shape resembling the article is coupled to an article support via a cable. In U.S. Pat. No. 3,540,968, a base has a similar shape to the article, and is driven by a chain and pinion. In the decoration of oval articles, matching velocities are attained by providing a turret having a radius equal to the radius of the article side to be decorated. U.S. Pat. Nos. 3,861,986 to Wochner; 3,823,218 to Geurtsen.
Web registration is another consideration in transfer labelng. It is desired to position the label at a particular place on the article, and to maintain placement over many successive transfers. U.S. Pat. Nos. 4,452,659 to Guertsen, and 4,381,211 to Nechay are illustrative of one method, whereby the web is driven by a roller in response to signals from an optical sensor. Accordingly, an additional consideration is the alignment, or indexing of round articles, to present a predetermined portion of the article circumference to the web at the start of transfer. In the prior art, a separate station is maintained, whereby the article is rotated by pins cooperative with recesses in the article underside. After indexing, the article is pushed to the decorating station.
Accordingly, it is an object of the invention to provide for matching the velocity of the web with the article periphery, without the need for adjusting the rotational velocity of the article during decoration.
It is a further object of the invention to provide for registration of the web with respect to the article, while independently varying the web velocity.
Another object of the invention is to avoid delays attendant with a separate article indexing station, by indexing the article as it is conveyed to a decorating site.
An additional object of the invention is to enable modification of relative web and article movements before, after, and during decoration, without replacement or modification of mechanical elements.
A further object is to avoid the requirement of matched turret and article radii in the decoration of ovals and other articles.
It is an additional object of the invention to provide a transfer decorator which is faster, more reliable, and simpler to operate than apparatus of the prior art.